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What can you do with a 1502?
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I pulled a 1502 TDR out of the buck a pound box at Dayton a few years back
and finally got it completely fixed the other week. I had to fab a battery pack and then fix the charging circuitry, but otherwise it was fine. Turned out I had an immediate need for it to measure how much coax I had left on a roll (answer: exactly enough to do a job). Pretty handy getting an answer without having to string the cable or unrolling the entire reel and finding out I'm a foot short. Anyone have any neat applications for one of these, other than the obvious ones of finding cable breaks and identifying where connectors are? -- Paul Amaranth, GCIH | Rochester MI, USA Aurora Group, Inc. | Security, Systems & Software paul@... | Unix & Windows |
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Hi Paul,
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It has lots of uses. Get the Tek book Time Domain Reflectrometry Measurements for insights. I use it to test every cable, connector, and adapter I buy from ham fests the Chinese, and anyone else. It doesn't go into my drawer until I confirmed it is stable, the connections are sound, and the impediance is 50 Ohms (or not more than 53 ohms if you are dealing with RG-53. Dennis Tillman W7PF -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Paul Amaranth Sent: Tuesday, February 27, 2018 1:57 PM To: [email protected] Subject: [TekScopes] What can you do with a 1502? I pulled a 1502 TDR out of the buck a pound box at Dayton a few years back and finally got it completely fixed the other week. I had to fab a battery pack and then fix the charging circuitry, but otherwise it was fine. Turned out I had an immediate need for it to measure how much coax I had left on a roll (answer: exactly enough to do a job). Pretty handy getting an answer without having to string the cable or unrolling the entire reel and finding out I'm a foot short. Anyone have any neat applications for one of these, other than the obvious ones of finding cable breaks and identifying where connectors are? -- Paul Amaranth, GCIH | Rochester MI, USA Aurora Group, Inc. | Security, Systems & Software paul@... | Unix & Windows -- Dennis Tillman W7PF TekScopes Moderator |
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On Tue, 27 Feb 2018 16:57:17 -0500, you wrote:
I pulled a 1502 TDR out of the buck a pound box at Dayton a few years back You are quite lucky. The tunnel diode is very fragile and directly connected to the BNC. (I'm thinking of the 1502, not sure about the later revisions). There should be a shorting BNC connector that needs to be on at all times unless you're doing a measurement. The tunnel diode can be damaged by DC (a typical damage scenario) or by RF transmitted into the TDR. The 1503 is harder to damage, doesn't use a tunnel diode, has a different presentation on the screen, but is for cables about 10x longer. Determining the velocity factor of the cable, for one. I think you can also determine the impedance of a cable as well. Again, be really careful with this, simply because the tunnel diode is unobtainable (period, sincerely yours, etc....). There *may* be a Russian equivalent, but I've not heard of one offhand. Mine needed battery packs, too. Harvey |
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Thanks Harvey, I'm aware of the TD issue. Frankly, I was surprised that
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it was OK. There was a thread on eevblog where one fellow used a Russion 1|308E as the 20mA and a A|201V for the 10mA diode. Sorry, I can't get the Cyrilic in correctly. I have a pack of the A|201V, I think. You can get 4 of those for $9, maybe less, on ebay (search for au201v). Haven't found the 1|308Es yet. Here's the eevblog thread: That was 4 years ago. Some other ones might work. Thanks for the pointer Dennis, I'll track down a copy. Paul On Tue, Feb 27, 2018 at 05:41:09PM -0500, Harvey White wrote:
On Tue, 27 Feb 2018 16:57:17 -0500, you wrote:I pulled a 1502 TDR out of the buck a pound box at Dayton a few years back --
Paul Amaranth, GCIH | Rochester MI, USA Aurora Group, Inc. | Security, Systems & Software paul@... | Unix & Windows |
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On 27/02/18 21:57, Paul Amaranth wrote:
I pulled a 1502 TDR out of the buck a pound box at Dayton a few years backNot just breaks, any discontinuity. I've used it to diagnose a fault in a relative's 75ohm TV antenna feed, where one multiplex couldn't be received. There was a bad kink 4m into the cable, and the impedance change notch filtered the multiplex's frequency. Given the resolution, it can also be used to diagnose impedance variations on a PCB; that's obviously not possible with the 1502B or 1502C. Occasionally, since it my fastest scope by about decade, I'm tempted use it to measure the risetime of my step generator. Obviously extreme care would be needed to avoid damaging the TD, but I think it could be done. And, shades of Dennis Tillman, vendors at hamfests are beginning to remember me :) The 1502s are sweet little things. |
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Hi. Several years ago, I, (for some bizarre reason) became rather obsessed with TDRs. I have 3 towers at my location with antennas from 160M through 70CM. I was able to accumulate a LOT of 1502 and 1503 TDRs, in addition to a bunch of Biddle, etc.
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When I install a new antenna, I always make several runs with the HP TDR and it's printout. I then store it and go back every year or so, to see if things have changed. Yes, the batteries are NFG and the TD are problematic. However, through ePay, I have scored a bunch of NOS TDs from both HP and the Russian equivalent. ron N4UE -----Original Message-----
From: Tom Gardner <tggzzz@...> To: TekScopes <[email protected]> Sent: Tue, Feb 27, 2018 6:59 pm Subject: Re: [TekScopes] What can you do with a 1502? On 27/02/18 21:57, Paul Amaranth wrote: I pulled a 1502 TDR out of the buck a pound box at Dayton a few years backNot just breaks, any discontinuity. I've used it to diagnose a fault in a relative's 75ohm TV antenna feed, where one multiplex couldn't be received. There was a bad kink 4m into the cable, and the impedance change notch filtered the multiplex's frequency. Given the resolution, it can also be used to diagnose impedance variations on a PCB; that's obviously not possible with the 1502B or 1502C. Occasionally, since it my fastest scope by about decade, I'm tempted use it to measure the risetime of my step generator. Obviously extreme care would be needed to avoid damaging the TD, but I think it could be done. And, shades of Dennis Tillman, vendors at hamfests are beginning to remember me :) The 1502s are sweet little things. |
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